Assembly comprising sheet heating element and delivery device

ABSTRACT

A vaporizing assembly for an aerosol generating system includes a sheet heating element and a delivery device configured to deliver a liquid aerosol-forming substrate from a liquid storing portion to the sheet heating element. The sheet heating element is spaced apart from the delivery device and is configured to heat the delivered liquid aerosol forming substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application of U.S. application Ser. No.16/288,569, filed Feb. 28, 2019, which is a continuation application ofU.S. application Ser. No. 15/474,136, filed Mar. 30, 2017, which claimspriority to PCT/EP2017/057015 filed on Mar. 23, 2017, and further claimspriority to EP 16163418.3 filed on Mar. 31, 2016; the entire contents ofeach of which are hereby incorporated herein by reference in theirentirety.

BACKGROUND

Aerosol generating systems may comprise a liquid storing portion forstoring a liquid aerosol-forming substrate and an electrically operatedvaporizer including a heating element for vaporizing the aerosol-formingsubstrate. An aerosol is generated when the vaporized aerosol-formingsubstrate condenses in an airflow passing the heating element. Theliquid aerosol-forming substrate is supplied to the heating element by awick having a set of fibers coupled to the liquid storing portion. Itmay be challenging to control the amount of aerosol-forming substratethat is supplied to the heating element and is to be incorporated in thegenerated aerosol.

It would be desirable to provide a vaporizing assembly for an aerosolgenerating system and a delivery system that provide some control of theamount of vaporized aerosol-forming substrate in the generated aerosol.Moreover, it would be desirable to achieve repeatability of generatingan aerosol with a desired (or, alternatively a predetermined) amount ofvaporized aerosol-forming substrate.

SUMMARY

At least one example embodiment relates to a vaporizing assembly for anaerosol generating system and a delivery system for evaporating a liquidaerosol-forming substrate. At least one example embodiment relates tohandheld aerosol generating systems such as electrically operatedaerosol generating systems.

In at least one example embodiment, a vaporizing assembly for an aerosolgenerating system comprises a heating element including a sheet heatingelement including a plurality of electrically conductive fibers; aliquid storing portion configured to store a liquid aerosol formingsubstrate therein; and a delivery device configured to deliver theliquid aerosol-forming substrate from the liquid storing portion to theheating element. The heating element is spaced apart from the deliverydevice. The heating element is configured to heat the delivered liquidaerosol forming substrate to form an aerosol

In at least one example embodiment, an aerosol generating systemcomprises a vaporizing assembly and an operation unit configured todetect an operation to initiate aerosol generation. The vaporizingassembly includes a heating element including a sheet heating element; aliquid storing portion configured to store a liquid aerosol formingsubstrate therein; and a delivery device configured to deliver theliquid aerosol-forming substrate from the liquid storing portion to theheating element. The heating element is spaced apart from the deliverydevice. The heating element is configured to heat the delivered liquidaerosol forming substrate to form an aerosol.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments will now be described, by way of example only, withreference to the accompanying drawings.

FIG. 1 is a schematic view of a vaporizing assembly in accordance withat least one example embodiment.

FIG. 2 is a schematic illustration of a spraying jet generated by avaporizing assembly in accordance with at least one example embodiment.

FIG. 3 is a schematic view of an aerosol generating system in accordancewith at least one example embodiment.

Throughout the figures, the same reference signs will be assigned to thesame or similar components and features.

DETAILED DESCRIPTION

Various example embodiments will now be described more fully withreference to the accompanying drawings in which some example embodimentsare shown. However, specific structural and functional details disclosedherein are merely representative for purposes of describing exampleembodiments. Thus, the embodiments may be embodied in many alternateforms and should not be construed as limited to only example embodimentsset forth herein. Therefore, it should be understood that there is nointent to limit example embodiments to the particular forms disclosed,but on the contrary, example embodiments are to cover all modifications,equivalents, and alternatives falling within the scope.

In the drawings, the thicknesses of layers and regions may beexaggerated for clarity, and like numbers refer to like elementsthroughout the description of the figures.

Although the terms first, second, etc. may be used herein to describevarious elements, these elements should not be limited by these terms.These terms are only used to distinguish one element from another. Forexample, a first element could be termed a second element, and,similarly, a second element could be termed a first element, withoutdeparting from the scope of example embodiments. As used herein, theterm “and/or” includes any and all combinations of one or more of theassociated listed items.

It will be understood that, if an element is referred to as being“connected” or “coupled” to another element, it can be directlyconnected, or coupled, to the other element or intervening elements maybe present. In contrast, if an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present. Other words used to describe therelationship between elements should be interpreted in a like fashion(e.g., “between” versus “directly between,” “adjacent” versus “directlyadjacent,” etc.).

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of exampleembodiments. As used herein, the singular forms “a,” “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises,” “comprising,” “includes” and/or “including,” if usedherein, specify the presence of stated features, integers, steps,operations, elements and/or components, but do not preclude the presenceor addition of one or more other features, integers, steps, operations,elements, components and/or groups thereof.

Spatially relative terms (e.g., “beneath,” “below,” “lower,” “above,”“upper” and the like) may be used herein for ease of description todescribe one element or a relationship between a feature and anotherelement or feature as illustrated in the figures. It will be understoodthat the spatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, for example, the term “below” can encompass both anorientation that is above, as well as, below. The device may beotherwise oriented (rotated 90 degrees or viewed or referenced at otherorientations) and the spatially relative descriptors used herein shouldbe interpreted accordingly.

Example embodiments are described herein with reference tocross-sectional illustrations that are schematic illustrations ofidealized embodiments (and intermediate structures). As such, variationsfrom the shapes of the illustrations as a result, for example, ofmanufacturing techniques and/or tolerances, may be expected. Thus,example embodiments should not be construed as limited to the particularshapes of regions illustrated herein but may include deviations inshapes that result, for example, from manufacturing. For example, animplanted region illustrated as a rectangle may have rounded or curvedfeatures and/or a gradient (e.g., of implant concentration) at its edgesrather than an abrupt change from an implanted region to a non-implantedregion. Likewise, a buried region formed by implantation may result insome implantation in the region between the buried region and thesurface through which the implantation may take place. Thus, the regionsillustrated in the figures are schematic in nature and their shapes donot necessarily illustrate the actual shape of a region of a device anddo not limit the scope.

It should also be noted that in some alternative implementations, thefunctions/acts noted may occur out of the order noted in the figures.For example, two figures shown in succession may in fact be executedsubstantially concurrently or may sometimes be executed in the reverseorder, depending upon the functionality/acts involved.

Although corresponding plan views and/or perspective views of somecross-sectional view(s) may not be shown, the cross-sectional view(s) ofdevice structures illustrated herein provide support for a plurality ofdevice structures that extend along two different directions as would beillustrated in a plan view, and/or in three different directions aswould be illustrated in a perspective view. The two different directionsmay or may not be orthogonal to each other. The three differentdirections may include a third direction that may be orthogonal to thetwo different directions. The plurality of device structures may beintegrated in a same electronic device. For example, when a devicestructure (e.g., a memory cell structure or a transistor structure) isillustrated in a cross-sectional view, an electronic device may includea plurality of the device structures (e.g., memory cell structures ortransistor structures), as would be illustrated by a plan view of theelectronic device. The plurality of device structures may be arranged inan array and/or in a two-dimensional pattern.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which example embodiments belong. Itwill be further understood that terms, such as those defined in commonlyused dictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

Unless specifically stated otherwise, or as is apparent from thediscussion, terms such as “processing” or “computing” or “calculating”or “determining” or “displaying” or the like, refer to the action andprocesses of a computer system, or similar electronic computing device,that manipulates and transforms data represented as physical, electronicquantities within the computer system's registers and memories intoother data similarly represented as physical quantities within thecomputer system memories or registers or other such information storage,transmission or display devices.

As disclosed herein, the term “storage medium”, “computer readablestorage medium” or “non-transitory computer readable storage medium,”may represent one or more devices for storing data, including read onlymemory (ROM), random access memory (RAM), magnetic RAM, core memory,magnetic disk storage mediums, optical storage mediums, flash memorydevices and/or other tangible machine readable mediums for storinginformation. The term “computer-readable medium” may include, but is notlimited to, portable or fixed storage devices, optical storage devices,and various other mediums capable of storing, containing or carryinginstruction(s) and/or data.

Furthermore, at least some portions of example embodiments may beimplemented by hardware, software, firmware, middleware, microcode,hardware description languages, or any combination thereof. Whenimplemented in software, firmware, middleware or microcode, the programcode or code segments to perform the necessary tasks may be stored in amachine or computer readable medium such as a computer readable storagemedium. When implemented in software, processor(s), processingcircuit(s), or processing unit(s) may be programmed to perform thenecessary tasks, thereby being transformed into special purposeprocessor(s) or computer(s).

A code segment may represent a procedure, function, subprogram, program,routine, subroutine, module, software package, class, or any combinationof instructions, data structures or program statements. A code segmentmay be coupled to another code segment or a hardware circuit by passingand/or receiving information, data, arguments, parameters or memorycontents. Information, arguments, parameters, data, etc. may be passed,forwarded, or transmitted via any suitable means including memorysharing, message passing, token passing, network transmission, etc.

In order to more specifically describe example embodiments, variousfeatures will be described in detail with reference to the attacheddrawings. However, example embodiments described are not limitedthereto.

In at least one example embodiment, a vaporizing assembly for an aerosolgenerating system comprises a sheet heating element and a deliverydevice configured to deliver a liquid aerosol-forming substrate from aliquid storing portion to the sheet heating element. The sheet heatingelement is spaced apart from the delivery device and is configured toheat the delivered liquid aerosol-forming substrate to a temperaturesufficient to volatilize at least a part of the delivered liquidaerosol-forming substrate. The sheet heating element is fluid permeableand comprises a plurality of electrically conductive filaments.

As used herein, a sheet heating element comprises a thin, substantiallyflat, electrically conductive material, such as a mesh of fibers, aconductive film, or an array of heating strips, suitable for receivingand heating an aerosol forming substrate for use in an aerosolgenerating system.

As used herein, “thin” means about 8 micrometers to about 2 millimeters,about 8 micrometers to about 500 micrometers, or about 8 micrometers toabout 100 micrometers. In the case of a mesh made up of filaments, thefilaments may have a diameter of less than about 40 micrometers.

As used herein, “substantially flat” means having a planar profile, suchthat it can be disposed in the vaporizing assembly spaced apart from thedelivery device and receive a jet or spray from the device substantiallyuniformly across the heating element. However, in some exampleembodiments, the sheet heating element may be curved in order tooptimize the delivery of the substrate, depending on the characteristicsof the delivery distribution of the delivery device. Accordingly, the“substantially flat” characteristic of the sheet heating elementpertains to the form of the element in its manufacture, but notnecessarily to its arrangement in the vaporizing assembly. In at leastone example embodiment, the sheet heating element is also in asubstantially flat orientation in the vaporizing assembly, spaced andopposed from the delivery device.

As used herein, “electrically conductive” means formed from a materialhaving a resistivity of about 1×10⁻⁴ ohm meters, or less.

The sheet heating element comprises a plurality of openings. In at leastone example embodiment, the sheet heating element may comprise a mesh offibers with interstices between them. The sheet heating element maycomprise a thin film or plate, optionally perforated with small holes.The sheet heating element may comprise an array of narrow heating stripsconnected in series.

The sheet heating element has a surface area of less than or equal toabout 100 square millimeters, allowing the sheet heating element to beincorporated in to a handheld system. The sheet heating element may,have a surface area of less than or equal to about 50 squaremillimeters.

In at least one example embodiment, electrically conductive filamentsare arranged in a mesh to form the sheet heating element, having a sizeranging from about 160 Mesh US to about 600 Mesh US (+/−10%) (e.g.,ranging from about 400 filaments per centimeter to about 1500 filamentsper centimeter (+/−10%)). The width of the interstices ranges from about10 micrometers to about 200 micrometers, or from about 25 micrometers toabout 75 micrometers. The percentage of open area of the mesh, which isthe ratio of the area of the interstices to the total area of the mesh,ranges from about 25 percent to about 56 percent. The mesh may be formedusing different types of weave or lattice structures. In at least oneexample embodiment, the electrically conductive filaments consist of anarray of filaments arranged parallel to one another.

In at least one example embodiment, an electrically conductive film orplate may form the sheet heating element. The film or plate may be madeof metal, conductive plastic, or other appropriate conductive material.In at least one example embodiment, the plate of film is perforated withholes that have a size on the order of interstices as described in themesh embodiment above.

In at least one example embodiment, narrow heating strips may becombined in an array to form the sheet heating element. The smaller thewidth of the heating strips in an array, the more heating strips may beconnected in series in the sheet heating element of the presentinvention. When using smaller width heating strips that are connected inseries, the electric resistance of their combination into the sheetheating element is increased.

The delivery device comprises an inlet and an outlet. The deliverydevice is configured to receive a liquid aerosol forming substrate at aninlet and to output, at an outlet, an amount of the liquid aerosolforming substrate to be delivered to the sheet heating element.

The sheet heating element is configured to heat the delivered liquidaerosol-forming substrate to a temperature sufficient to volatilize atleast a part of the delivered liquid aerosol-forming substrate.

The sheet heating element is spaced apart from the delivery device. Asused herein, “spaced apart” means that the vaporizing assembly isconfigured to deliver the liquid aerosol-forming substrate from thedelivery device via an air gap to the sheet heating element. Spacedapart also means that the delivery device and the sheet heating elementare not coupled by a tubing segment for leading flow of the liquidaerosol forming substrate from the delivery device to the heatingelement. Spaced apart may also mean that the delivery device and thesheet heating element are provided as individual members separated fromeach other by an air gap. The term spaced apart includes an integralcombination of the delivery device and the sheet heating element into acombined component as long as the liquid aerosol-forming substrate hasto pass through an air gap within this combined component immediatelybefore being heated by the sheet heating element.

By providing the sheet heating element spaced apart from the deliverydevice, the amount of liquid aerosol forming substrate delivered to theheating element may be better controlled compared to a vaporizer havinga tubing segment configured to lead flow of the liquid aerosol formingsubstrate from the delivery device to the heating element. Capillaryactions due to use of a tubing segment may be avoided which mightotherwise, for example, give rise to movement of liquid between theheating element and the delivery device. When passing the air gap thedelivered amount of the liquid aerosol-forming substrate may betransformed into a jet of droplets before hitting the surface of thesheet heating element. Thus, a uniform distribution of the deliveredamount of the liquid aerosol forming substrate on the sheet heatingelement may be enhanced, leading to better controllability andrepeatability of generating an aerosol with a desired (or, alternativelypredetermined) amount of vaporized aerosol forming substrate perinhalation cycle.

The operating temperature of the sheet heating element may range fromabout 120 degrees Celsius to about 210 degrees Celsius, or from about150 degrees Celsius to about 180 degrees Celsius.

The sheet heating element comprises a plurality of electricallyconductive filaments. In at least one example embodiment, the sheetheating element is a mesh heating element, comprising the plurality ofelectrically conductive filaments. The plurality of electricallyconductive filaments forms a mesh of the mesh heating element. The meshis heated by applying electric power to the plurality of electricallyconductive filaments. The sheet heating element may comprise a pluralityof filaments which can be made of a single type of fibers, such asresistive fibers, as well as a plurality of types of fibers, includingcapillary fibers and conductive fibers.

The electrically conductive filaments may comprise any suitableelectrically conductive material. Suitable materials include but are notlimited to: semiconductors such as doped ceramics, electrically“conductive” ceramics (such as, for example, molybdenum disilicide),carbon, graphite, metals, metal alloys and composite materials made of aceramic material and a metallic material. Such composite materials maycomprise doped or undoped ceramics. Examples of suitable doped ceramicsinclude doped silicon carbides. Examples of suitable metals includetitanium, zirconium, tantalum and metals from the platinum group.Examples of suitable metal alloys include stainless steel, constantan,nickel-, cobalt-, chromium-, aluminium- titanium- zirconium-, hafnium-,niobium-, molybdenum-, tantalum-, tungsten-, tin-, gallium-, manganese-and iron-containing alloys, and super-alloys based on nickel, iron,cobalt, stainless steel, Timetal®, iron-aluminium based alloys andiron-manganese-aluminium based alloys. Timetal® is a registered trademark of Titanium Metals Corporation. The filaments may be coated withone or more insulators. The electrically conductive filaments made beformed of 304, 316, 304L, and 316L stainless steel, and graphite.

The electrical resistance of the plurality of electrically conductivefilaments of the mesh heating element may range from about 0.3 Ohms toabout 4 Ohms. In at least one example embodiment, the electricalresistance of the plurality of electrically conductive filaments rangesfrom about 0.5 Ohms to about 3 Ohms, or about 1 Ohm. The electricalresistance of the plurality of electrically conductive filaments is atleast an order of magnitude, or at least two orders of magnitude,greater than the electrical resistance of electrical contact portions ofthe mesh heating element. This ensures that the heat generated bypassing current through the mesh heating element is localized to theplurality of electrically conductive filaments.

The electrically conductive filaments may define interstices between thefilaments and the interstices may have a width ranging from about 10micrometers to about 100 micrometers. In at least one exampleembodiment, the filaments give rise to capillary action in theinterstices, so that liquid to be vaporized is drawn into theinterstices thereby increasing the contact area between the heaterassembly and the liquid.

The mesh of electrically conductive filaments may also be characterizedby its ability to retain liquid.

In at least one example embodiment, the mesh heating element comprisesat least one filament made from a first material and at least onefilament made from a second material different from the first material.This may be beneficial for electrical or mechanical reasons. In at leastone example embodiment, one or more of the filaments may be formed froma material having a resistance that varies significantly withtemperature, such as an iron aluminum alloy. This allows a measure ofresistance of the filaments to be used to determine temperature orchanges in temperature. This can be used in a puff detection system andfor controlling temperature of the heating element to keep it within adesired temperature range.

The sheet heating element is fluid permeable. As used herein, fluidpermeable in relation to a sheet heating element means that the aerosolforming substrate, in a gaseous phase and possibly in a liquid phase,can readily pass through the sheet heating element. Including a fluidpermeable heater may enhance surface area and improve vaporization. Inaddition, a fluid permeable heater may also allow improved mixing ofvaporized liquid aerosol forming substrate with an air flow.

In at least one example embodiment, the sheet heating element issubstantially flat. As used herein, substantially flat means formed in asingle plane and not wrapped around or other conformed to fit a curvedor other non-planar shape. A flat heating element can be easily handledduring manufacture and provides for a robust construction.

In at least one example embodiment, where the sheet heating element is amesh heating element, the mesh heating element may comprise a pluralityof mesh layers stacked in an intended direction of airflow through themesh heating element. Each mesh layer can be easily handled duringmanufacture and provides for a robust construction. Moreover, thestacked mesh layers improve vaporization of the liquid aerosol formingsubstrate.

In at least one example embodiment, the sheet heating element has asquare geometry. The sheet heating element may have a heating area witha square geometry with dimensions of each side within a range of about 3millimeters to about 7 millimeters, or from about 4 millimeters to about5 millimeters.

The sheet heating element may comprise a plurality of narrow heatingstrips arranged spaced apart from each other on a plane. The heatingstrips are in a rectangular shape and spatially arranged substantiallyparallel to each other. The heating strips may be electrically connectedin series. By appropriate spacing of the heating strips, a more evenheating may be obtained compared with for example where a sheet heatingelement having the same area is used.

In at least one example embodiment, the delivery device is configured todeliver a desired (or, alternatively predetermined) amount of the liquidaerosol-forming substrate to the sheet heating element upon performingone activation cycle. The desired (or, alternatively predetermined)amount of the liquid aerosol-forming substrate is delivered via the airgap from the delivery device to the sheet heating element. By depositingthe liquid aerosol-forming substrate onto the sheet heating elementdirectly, the liquid aerosol-forming substrate may remain substantiallyin its liquid state until it reaches the sheet heating element, althoughsmall droplets near the element may aerosolize before contacting thesheet heating element. The desired (or, alternatively predetermined)amount of the liquid aerosol-forming substrate may be an amountequivalent to produce a desired volume of aerosol in the sheet heatingelement.

In at least one example embodiment, the delivery device is configured tospray the liquid aerosol forming substrate onto the sheet heatingelement as a spraying jet with a size and shape appropriate to thegeometry of the sheet heating element. The delivery device may beconfigured to spray the liquid aerosol forming substrate onto the sheetheating element to cover at least 90 percent or at least 95 percent, ofan upstream surface of the sheet heating element facing the deliverydevice.

The delivery device may comprise an atomizer spray nozzle, in which casea flow of air is supplied through the nozzle by the action of puffing,which creates a pressurized air flow that will mix and act with theliquid creating an atomized spray in the outlet of the nozzle. Severalsystems including nozzles that work with small volumes of liquid areavailable, in sizes that meet the requirements to fit in small portabledevices. Another class of nozzle that may be used is an airless spraynozzle, sometimes referred to as a micro-spray nozzle. Such nozzlescreate micro spray cones in very small sizes. With this class ofnozzles, the airflow management inside the device, namely inside themouth piece, surrounds the nozzle and the heating element, flushing theheating element surface towards the outlet of the mouth piece, includinga turbulent air flow pattern of the aerosol exiting the mouth piece.

For either class of nozzle, the distance of the air gap between thedelivery device and the sheet heating element facing the nozzle, iswithin a range of from about 2 millimeters to about 10 millimeters, orfrom about 3 millimeters to about 7 millimeters. Any type of availablespraying nozzles may be used. Airless nozzle 062 Minstac frommanufacturer “The Lee Company” is an example of a suitable spray nozzle.

In at least one example embodiment, the delivery device comprises amicropump configured to pump the liquid aerosol-forming substrate from aliquid storage portion. By using the micropump instead of a capillarywick or any other passive medium to draw liquid, only the actuallyrequired amount of liquid aerosol-forming substrate may be transportedto the sheet heating element. Liquid aerosol-forming substrate may onlybe pumped upon demand, for example in response to a puff.

The micropump may allow on-demand delivery of liquid aerosol-formingsubstrate at a flow rate of about 0.7 microliters per second to about4.0 microliters per second for intervals of variable or constantduration. A pumped volume of one activation cycle may be around 0.5microliters in micropumps working within a pumping frequency rangingfrom about 8 hertz to about 15 hertz. In at least one exampleembodiment, the pump volume in each activation cycle, as a dose ofliquid aerosol-forming substrate per puff, may be of 0.4 microliters toabout 0.5 microliters.

The micropump may be configured to pump liquid aerosol-formingsubstrates that have a relatively high viscosity as compared to water.The viscosity of a liquid aerosol-forming substrate may be in the rangefrom about 15 millipascal seconds to about 500 millipascal seconds, orin the range from about 18 millipascal seconds to about 81 millipascalseconds.

In some example embodiments, the delivery device may comprise a manuallyoperated pump for pumping the liquid aerosol-forming substrate from aliquid storage portion. A manually operated pump reduces the number ofelectric and electronic components and thus, may simplify the design ofthe vaporizing assembly.

In at least one example embodiment, a vaporizing assembly suitable foran aerosol generating system comprises a sheet heating element and adelivery device configured to deliver a liquid aerosol-forming substratefrom a liquid storing portion to the sheet heating element. The sheetheating element is spaced apart from the delivery device and isconfigured to heat the delivered liquid aerosol-forming substrate to atemperature sufficient to volatilize at least a part of the deliveredliquid aerosol-forming substrate.

In at least one example embodiment, an aerosol generating systemcomprises the vaporizing assembly and an operation detection unitconfigure to detect an operation to initiate aerosol generation. Theoperation detection unit may include a puff detection system, e.g. apuff sensor. In at least one example embodiment, the operation detectionunit may include an on-off button, e.g. an electrical switch. The on-offbutton may be configured to trigger activation of at least one of themicropump and the heating element when being pressed down. A duration ofthe on-off button being pressed down may determine the duration ofactivation of at least one of the micropump and the heating element,e.g. by constantly pressing down the on-off button during a puff.

In at least one example embodiment, the aerosol generating systemfurther comprises a control unit which is configured to activate thedelivery device with a desired (or, alternatively predetermined) timedelay after activating the heating element in response to a detecteduser operation. Upon activation, such as using the on-off button or thepuff sensor, the control unit may activate the sheet heating elementfirst, and then, after delay of about 0.3 seconds to about 1 seconds, orfrom 0.5 seconds to about 0.8 seconds, may activate the delivery device.The duration of activation may be fixed or may correspond to an actionlike pressing the on-off button or puffing as, for example, detected bythe operation detection unit. In at least one example embodiment, thecontrol unit may be configured to activate the sheet heating element andthe delivery device simultaneously.

In at least one example embodiment, the aerosol generating system maycomprise a device portion and a replaceable liquid storage portion. Thedevice portion may comprise a power supply and the control unit. Thepower supply may be any type of electric power supply, typically abattery. The power supply for the delivery device may be different fromthe power supply of the sheet heating element or may be the same.

The aerosol generating system may further comprise electric circuitryconnected to the vaporizing assembly and to the power supply which is anelectrical power source. The electric circuitry may be configured tomonitor the electrical resistance of the sheet heating element, and tocontrol the supply of power to the sheet heating element dependent onthe electrical resistance of the sheet heating element.

The electric circuitry may comprise a controller with a microprocessor,which may be a programmable microprocessor. The electric circuitry maycomprise further electronic components. The electric circuitry may beconfigured to regulate a supply of power to the vaporizing assembly.Power may be supplied to the vaporizing assembly continuously followingactivation of the system or may be supplied intermittently, such as on apuff-by-puff basis. The power may be supplied to the vaporizing assemblyin the form of pulses of electrical current.

The power supply may be a form of charge storage device such as acapacitor, a super-capacitor, or hyper-capacitor. The power supply mayrequire recharging and may have a capacity that allows for the storageof enough energy; for example, the power supply may have sufficientcapacity to allow for the continuous generation of aerosol for a periodof around six minutes or for a period that is a multiple of six minutes.In at least one example embodiment the power supply may have sufficientcapacity to allow for a desired (or, alternatively predetermined) numberof puffs or discrete activations of the vaporizing assembly.

For allowing air to enter the aerosol generating system, a wall of thehousing of the aerosol generating system, such as a wall opposite thevaporizing assembly or a bottom wall, is provided with at least onesemi-open inlet. The semi-open inlet allows air to enter the aerosolgenerating system, but does not allow air or liquid to leave the aerosolgenerating system through the semi-open inlet. A semi-open inlet may bea semi-permeable membrane, permeable in one direction only for air, butis air- and liquid-tight in the opposite direction. A semi-open inletmay also be a one-way valve. In at least one example embodiment, thesemi-open inlets allow air to pass through the inlet only if specificconditions are met, for example a reduced and/or minimum depression inthe aerosol generating system or a volume of air passing through thevalve or membrane.

The liquid aerosol-forming substrate is a substrate that releasesvolatile compounds that can form an aerosol. The volatile compounds maybe released by heating the liquid aerosol-forming substrate. The liquidaerosol-forming substrate may comprise plant-based material. The liquidaerosol-forming substrate may comprise tobacco. The liquidaerosol-forming substrate may comprise a tobacco-containing materialcontaining volatile tobacco flavor compounds, which are released fromthe liquid aerosol-forming substrate upon heating. The liquidaerosol-forming substrate may alternatively comprise anon-tobacco-containing material.

The liquid aerosol-forming substrate may comprise homogenizedplant-based material. The liquid aerosol-forming substrate may comprisehomogenized tobacco material. The liquid aerosol-forming substrate maycomprise at least one aerosol-former. The liquid aerosol-formingsubstrate may comprise other additives and ingredients, such asflavorants.

The aerosol generating system may be an electrically operated system. Inat least one example embodiment, the aerosol generating system isportable. The aerosol generating system may have a size comparable to acigar or cigarette. The system may have a total length ranging fromabout 45 millimeters to about 160 millimeters. The system may have anexternal diameter ranging from about 7 millimeters to about 25millimeters.

At least one example embodiment relates to a method for generating anaerosol. The method comprises heating a sheet heating element; anddelivering, by a delivery device spaced apart from the sheet heatingelement, a liquid aerosol-forming substrate to the sheet heatingelement. The delivered liquid aerosol-forming substrate is heated by thesheet heating element to a temperature sufficient to volatilize at leasta part of the delivered liquid aerosol-forming substrate.

Features described in relation to one aspect may equally be applied toother aspects of the invention.

In at least one example embodiment, as shown in FIG. 1 , a vaporizingassembly 1 comprises a sheet heating element 2 and a delivery device 3incorporated into a common housing 10. The delivery device 3 includes amicropump 6 and a spray nozzle 5 connected by a tubing segment 12. Themicropump 6 is configured to receive, via the tubing segment 11, aliquid aerosol forming substrate from a replaceable liquid storingportion 8. The delivery device 3 is spaced apart from the mesh heaterelement 2. The delivery device 3 and the mesh heater element 2 areseparated by an air gap having a length D between an outlet 5A of thespray nozzle 5 and the upstream surface 2A of the sheet heating element2 facing the spray nozzle 5. The spray nozzle 5 is configured to receivean amount of the liquid aerosol forming substrate pumped from themicropump 6 via tubing segment 12 and to spray the amount of liquidaerosol forming substrate as a spraying jet 4S onto the upstream surface2A of the sheet heating element 2. The spray nozzle 5 is configured togenerate the spraying jet 4S such that the amount of liquidaerosol-forming substrate is completely received by the sheet heatingelement 2 and covers the entire upstream surface 2A of the sheet heatingelement 2. The housing 10 comprises an air inlet 4 allowing air 15 topass from outside the housing 10 into the vaporizing assembly 1 towardsthe upstream surface 2A of the sheet heating element 2. The sheetheating element 2 is configured to allow the air 15 that enters from airinlet 4 to pass towards a downstream surface 2B of the sheet heatingelement 2 opposite from the spray nozzle 5. Having passed through thesheet heating element 2, the air 15 combines with the aerosol formingsubstrate vaporized by the sheet heating element 2 to form an aerosol16.

In at least one example embodiment, as shown in FIG. 2 , a spraying jetis generated by a vaporizing assembly. The spraying jet 4S output fromthe outlet 5A of the spray nozzle 5 of the vaporizing assemblyillustrated in FIG. 1 has a size and shape fitted to the geometry of theupstream surface 2A of the sheet heating element 2. The upstream surface2A has a square shape. The spraying jet 4S exhibits substantially thesame square shape. The size of the spraying jet 4S arriving at theupstream surface 2A is the same as the size of the upstream surface 2A.

In at least one example embodiment, as shown in FIG. 3 , an aerosolgenerating system 20 comprises the vaporizing assembly 1 as illustratedin FIG. 1 and is configured to generate a spraying jet as shown in FIG.2 . Moreover, the aerosol generating system 20 comprises a liquidstoring portion embodied by a replaceable container 8, an electroniccontrol unit 9, a battery unit 13, wiring components 14 for electricallyconnecting the battery unit 13, the electronic control unit 9 and theelectrically driven components of the vaporizing assembly 1, i.e. thesheet heating element 2 and the micropump 6. A replaceable mouth piece17 having an air flow outlet 18 is coupled to the housing 10.

Various modifications and variations of the invention will be apparentto those skilled in the art without departing from the scope and spiritof the invention. Although the invention has been described inconnection with specific embodiments, it should be understood that theinvention as claimed should not be unduly limited to such specificembodiments. Indeed, various modifications of the described modes forcarrying out the invention which are apparent to those skilled in themechanical arts, electrical arts, and aerosol generating articlemanufacturing or related fields are intended to be within the scope ofthe following claims.

We claim:
 1. An assembly for an aerosol generating system, the assemblycomprising: a heating element; a liquid storing portion configured tostore a liquid aerosol-forming substrate therein; and a delivery deviceconfigured to deliver the liquid aerosol-forming substrate from theliquid storing portion to the heating element, the delivery devicebetween the liquid storing portion and the heating element, the deliverydevice and the heating element defining an air gap therebetween, thedelivery device including, a micropump, and an airless spray nozzle, themicropump configured to deliver the liquid aerosol-forming substratefrom the liquid storing portion to the heating element via the airlessspray nozzle, the airless spray nozzle configured to generate a sprayingjet, such that an amount of the liquid aerosol-forming substrate sprayedby the airless spray nozzle is completely received by the heatingelement.
 2. The assembly according to claim 1, wherein the air gapranges from 2 millimeters to 10 millimeters in length.
 3. The assemblyaccording to claim 1, wherein the heating element is a mesh heater. 4.The assembly according to claim 3, wherein the heating element has arectangular geometry.
 5. The assembly according to claim 4, wherein theheating element has a square geometry.
 6. The assembly according toclaim 3, wherein the delivery device is configured to spray the liquidaerosol-forming substrate onto the heating element as a spray having asize and shape fitted to a geometry of the heating element.
 7. Anaerosol generating system, comprising: an assembly including, a heatingelement, a liquid storing portion configured to store a liquidaerosol-forming substrate therein, and a delivery device configured todeliver the liquid aerosol-forming substrate from the liquid storingportion to the heating element, the delivery device between the liquidstoring portion and the heating element, the delivery device and theheating element defining an air gap therebetween, the delivery deviceincluding, a micropump, and an airless spray nozzle, the micropumpconfigured to deliver the liquid aerosol-forming substrate from theliquid storing portion to the heating element via the airless spraynozzle, the airless spray nozzle configured to generate a spraying jet,such that an amount of the liquid aerosol-forming substrate sprayed bythe airless spray nozzle is completely received by the heating element;and a device portion including, a power supply and configured toselectively supply power to the heating element from the power supply.8. The aerosol generating system according to claim 7, furthercomprising: a control unit configured to activate the delivery devicewith a time delay after activating the heating element.
 9. The aerosolgenerating system according to claim 8, therein the power supplyincludes the control unit.
 10. The aerosol generating system accordingto claim 7, wherein the heating element is a mesh heater.
 11. Theaerosol generating system according to claim 10, wherein the heatingelement has a rectangular geometry.
 12. The aerosol generating systemaccording to claim 11, wherein the heating element has a squaregeometry.